Update comments
We no longer put the filename at start of file.
Change-Id: Ic435b159a23105681e3d4a6cb1ac097bc853302e
diff --git a/include/private/media/AudioTrackShared.h b/include/private/media/AudioTrackShared.h
index 23226c0..af2db93 100644
--- a/include/private/media/AudioTrackShared.h
+++ b/include/private/media/AudioTrackShared.h
@@ -62,16 +62,23 @@
// are in the same line of data cache.
Mutex lock; // sizeof(int)
Condition cv; // sizeof(int)
+
+ // next 4 are offsets within "buffers"
volatile uint32_t user;
volatile uint32_t server;
uint32_t userBase;
uint32_t serverBase;
+
+ // if there is a shared buffer, "buffers" is the value of pointer() for the shared
+ // buffer, otherwise "buffers" points immediately after the control block
void* buffers;
uint32_t frameCount;
+
// Cache line boundary
+
uint32_t loopStart;
- uint32_t loopEnd;
- int loopCount;
+ uint32_t loopEnd; // read-only for server, read/write for client
+ int loopCount; // read/write for client
// Channel volumes are fixed point U4.12, so 0x1000 means 1.0.
// Left channel is in [0:15], right channel is in [16:31].
@@ -82,29 +89,39 @@
public:
uint32_t sampleRate;
+
// NOTE: audio_track_cblk_t::frameSize is not equal to AudioTrack::frameSize() for
// 8 bit PCM data: in this case, mCblk->frameSize is based on a sample size of
// 16 bit because data is converted to 16 bit before being stored in buffer
+ // read-only for client, server writes once at initialization and is then read-only
uint8_t frameSize; // would normally be size_t, but 8 bits is plenty
+
+ // never used
uint8_t pad1;
+
+ // used by client only
uint16_t bufferTimeoutMs; // Maximum cumulated timeout before restarting audioflinger
- uint16_t waitTimeMs; // Cumulated wait time
+ uint16_t waitTimeMs; // Cumulated wait time, used by client only
private:
+ // client write-only, server read-only
uint16_t mSendLevel; // Fixed point U4.12 so 0x1000 means 1.0
public:
volatile int32_t flags;
// Cache line boundary (32 bytes)
+ // Since the control block is always located in shared memory, this constructor
+ // is only used for placement new(). It is never used for regular new() or stack.
audio_track_cblk_t();
- uint32_t stepUser(uint32_t frameCount);
- bool stepServer(uint32_t frameCount);
+ uint32_t stepUser(uint32_t frameCount); // called by client only, where
+ // client includes regular AudioTrack and AudioFlinger::PlaybackThread::OutputTrack
+ bool stepServer(uint32_t frameCount); // called by server only
void* buffer(uint32_t offset) const;
uint32_t framesAvailable();
uint32_t framesAvailable_l();
- uint32_t framesReady();
+ uint32_t framesReady(); // called by server only
bool tryLock();
// No barriers on the following operations, so the ordering of loads/stores